Electronic products, for example, TVs, mobile phones, computers, portable music players and the like, include at least one printed circuit board (PCB). PCBs for electronic products undergo part assembly and inspection processes for electronic products in a preset fabrication line.
Barcode labels were used as an approach for managing the process of assembling electronic product PCBs (including the inspection process) of the related art. For instance, this method manages all processes including the assembly process by identifying barcodes printed on a barcode label using a scanner and updating the identified barcodes in a management server when one process is completed in the production line.
Describing the foregoing management method using barcode labels, there are restrictions in that the miniaturization of labels is limited, and that labels must be attached to positions where they can be exposed at any time to a scanner. In addition, scanning and processing time that reaches up to several tens of seconds can cause a time delay in the assembly process. If an electronic product PCB is small, trouble occurs in that the barcode label must be detached for the purpose of the parts assembly process and then reattached when the corresponding process is finished. Therefore, the subsequent process is delayed. For reference, the amount of processing time that is uselessly spent can be estimated considering the number of assembly steps and that the processes of attaching and detaching barcode labels are manually performed.
In order to overcome the problem of the barcode system, several electronic product manufacturers introduced radio frequency identification (RFID) tags. As is known, RFID tags are divided into active tags and passive tags depending on the presence of operating power. The active tag has limitations to miniaturization since it must include a power source (e.g. a battery). Accordingly, the passive tag which uses a radio wave radiated from an antenna of an RFID tag reader is widely used.
The passive tag basically includes a tag chip and an antenna. There are two methods of applying the passive tag to the above-mentioned electronic product PCB. One is to attach the RFID tag to the PCB like the barcode label, and the other one is to mount a passive tag on the electronic product PCB. The latter requires the electronic product PCB to be provided with an antenna pattern which is to be connected to the tag chip. This means a space on the PCB corresponding to the size of the antenna is required. It is difficult, however, to provide an antenna pattern space for the tag chip in a PCB of a small electronic product, for example, a portable phone.
As a related art for overcoming this problem, disclosed was United States Patent Application Publication No. US2010/0219941 “SYSTEM, APPARATUS, AND METHOD FOR PCB-BASED AUTOMATION TRACEABILITY” (hereinafter referred to as “'941 patent”). The '941 patent is significant in that a ground plane of a PCB is used as an antenna for a tag. Specifically, the antenna in '941 patent has a structure known as a “slot antenna.” As apparent from the figures in '941 patent, a slot formed at a preset length on the ground plane acts as an antenna. However, the length of the slot is required to be about 70 mm when an intended frequency is 900 MHz and an entire frequency wavelength is used and about 35 mm even if half a frequency wavelength is used.
However, considering the trends of PCBs toward small size and high integration that are becoming more demanding every day, the length of the slot has a significant effect on design conditions such as formation of traces (or signal patterns) or arrangement of components. For instance, the slot causes some traces to be designed to take a roundabout path instead of an optimum path. This has an effect over not only that trace but also arrangement of the other traces and components.